The present invention relates to an electronic apparatus, and particularly, to an electronic apparatus having an antenna, and an electronic element which generates heat.
With miniaturization of wireless communication apparatuses in recent years, miniaturization of electronic apparatuses to be loaded onto the wireless communication apparatuses is desired. As a miniaturized electronic apparatus, for example, one disclosed in Patent Document 1 is known. FIG. 1 is a view showing the schematic construction of the electronic apparatus 100 disclosed in Patent Document 1.
The electronic apparatus 100 shown in this drawing is constituted by a substrate 110, a semiconductor chip 115, copper core solder balls 118, etc. The substrate 110 is a double-sided printed circuit board. An antenna 112 is formed on the top face of a substrate body 111, and a wiring pattern 113 is formed on the bottom face of the substrate body. The antenna 112 and the wiring pattern 113 are connected together by a via 114.
The semiconductor chip 115 has bumps 116 formed thereon, and is flip-chip joined to pads formed in the wiring pattern 113 of the substrate 110. Further, underfill resin 117 is disposed between the semiconductor chip 115 and the substrate body 111. Furthermore, the ends of the wiring pattern 113 are provided with the copper core solder balls 118 which become external connecting terminals.
The electronic apparatus 100 constructed as above is mounted onto a mother board 119, as shown in FIG. 2. In this case, the electronic apparatus 100 is mounted onto the mother board 119 such that the semiconductor chip 115 faces the mother board 119, in other words, such that the antenna 112 be located outside.
Meanwhile, generally, the semiconductor chip 115 corresponding to high frequency, which is disposed along with the antenna 112, generates a lot of heat. Typically, a heat-radiating member (for example, radiating fins, etc.) is used for the cooling of the semiconductor chip which heat generates in this way. However, since the electronic apparatus 100 is adapted such that the semiconductor chip 115 faces the mother board 119 in a mounted state (refer to FIG. 2), the semiconductor chip 115 cannot be provided with the heat-radiating member.
Further, it is also considered that the heat-radiating member is provided on the face of the substrate 110 opposite to the face where the semiconductor chip 115 is disposed. However, in the electronic apparatus 100, the antenna 112 is formed on this opposite face. Therefore, this part cannot be provided with the heat-radiating member. For this reason, with the heat-radiating member, such as radiating fins, the heat generated in the semiconductor chip 115 cannot be effectively radiated.
Thus, as shown in FIG. 2, it is considered that a TIM 120 (heat-radiating material: Thermal Interface Material) is interposed between the semiconductor chip 115 and the mother board 119 in a mounted state, and thereby, the heat from the semiconductor chip 115 is radiated to the mother board 119. As this TIM 120, grease, elastomer (high polymer with elasticity) sheet, RTV (Room Temperature Vulcanization) rubber, etc. can be used. [Patent Document 1] JP-A-2007-266443
However, when this method is used actually, it is necessary to dispose the TIM 120 between the semiconductor chip 115 and the mother board 119 in advance before the copper core solder balls 118 are soldered to the mother board 119 by reflow processing. For this reason, the TIM 120 to be used needs reflow heat resistance. As a result, selection of the TIM 120 is limited, and an increase in the cost of the TIM 120 is expected.
Further, the thickness of TIM 120 is involved with the mountability of the copper core solder balls 118 and the mother board 119. That is, if the thickness of TIM 120 is larger than a rated value, a clearance may be created between the copper core solder balls 118 and the mother board 119, and the mounting reliability may deteriorate. In preventing this, there is a problem in that the thickness control of the TIM 120 should be performed accurately.